p62/SQSTM1 selectively supports starvation-induced autophagy in N2a neuroblastoma cells

Autophagy is a critical cellular process that maintains homeostasis and enables adaptation to metabolic stress. The selective autophagy receptor p62/SQSTM1 has been implicated in multiple aspects of autophagy regulation; however, its specific contribution to basal versus stress-induced autophagic flux remains incompletely defined, particularly in neuronal cells. In this study, we investigated the role of p62 in regulating basal and starvation-induced autophagy using a CRISPR Cas9 generated p62 knockout (p62 KO) neuroblastoma (N2a) cell model. Autophagic flux was quantified by measuring LC3 II accumulation in the presence and absence of the lysosomal inhibitor bafilomycin A1. Under nutrient-replete conditions, basal autophagic flux was comparable between wild-type and p62-deficient cells, indicating that p62 is dispensable for constitutive autophagy. In contrast, starvation robustly increased autophagic flux in wild-type cells but failed to do so in p62 KO cells, demonstrating a requirement for p62 in starvation-induced autophagy. Consistent with a stress-responsive role, p62 protein levels increased during starvation in wild-type cells under lysosomal inhibition, reflecting enhanced p62 expression rather than impaired degradation. Together, these findings reveal a context-dependent function for p62 in neuronal autophagy, whereby p62 is essential for mounting an effective autophagic response to nutrient deprivation but is not required for basal autophagic turnover.